Siemens SICLOCK DCFRS 2XV9450-1AR21/2XV9450-1AR48 - Handbuch (Seite 13)

User Manual SICLOCK DCFRS Industrial Version
Order No. 2XV9450-1AR48 Version 1.0 5
2.2 Connection
2.2.1 Target System
The interface between the target system and the antenna is provided by the TTY-RS232 converter. It
is connected to the target system via a RS232 interface. The other end of the cable is spit, the 4 wires
are provided with wire end ferrules. The AC adapter (output 14V AC) supplied is connected to the
white and brown wires. A direct current between 15V and 30V or an alternating current between 10V
and 20V can also be connected. There is a rectifier integrated in the converter and therefore there is
no need to take the polarity into account. The cable to be laid on site is connected to the yellow
and green lead (2-wire shielded, loop resistance less than 150 Ohm).
2.2.2 Antenna
The two antenna connections are connected in the second distribution box with the connecting cable
to the TTY-RS232 converter. Here, too, there is no need to take polarity into account. After starting
the reception service on the target system, the LED on the antenna must begin to flash in second tact.
Then the mounting of the antenna and its alignment can begin.
2.2.3 Cable Shield
The shield of the connection cable laid on site between the TTY-RS232 converter and the antenna
should be connected to one cable end low-resistance with the earth. Specially suitable for this are
earth bars from switch cabinet or water pipes. Under no circumstances should there be an earth on
both sides, as this can result in high potential equalizing currents over the cable shield.
2.3 Mounting
2.3.1 Choice of Location
Before beginning to mount the antenna the location for this should be selected with care. This is
significant for the quality of the reception and therefore of the availability of the DCF77 reception
signal. It can be at a maximum of 1000 m away from the unit to be synchronized. In selecting the
location, the following criteria should be optimized:
• Distance from electric equipment: Every electrical appliance sends out electro-magnetic
radiation which impairs reception. The antenna should therefore be set up as far away as possible from
electrical appliances. A particularly high disturbance level is caused by monitors, PCs, laser printers,
motor drives and neon tubes, and maximum distance should therefore be maintained from such
equipment. Care should also be taken that the antenna cable is not laid parallel to the output cables
(e.g. supply cable for motors).
• Shielding: Metal objects shield the reception signal and thus impair
quality of reception. As great a distance as possible should therefore be maintained to metal surfaces
and objects. It should also be noted that under certain circumstances, the steel reinforcement in
reinforced concrete weakens the field.
• Alignment to the transmitter: The transmitter which sends out the DCF77 time signal is
located near to Frankfurt. The steel which is incorporated in modern buildings weakens the reception
signal. In respect of optimum conditions for reception, the place of reception is preferably chosen on
the side facing Frankfurt. In addition, the antenna should be mounted as high as possible.
In order to find the optimum location for reception within the industrial premises we offer a survey of the
whole plant area. In this way as a rule, at least one location can be found which facilitates problem-free
and interference-free DCF77 reception. Just give us a call and we shall be pleased to help you.
2.3.2 Alignment to the Transmitter
As for a radio or television antenna, the DCF77 reception antenna must also be aligned to the
transmitter. To assess the quality of reception there is a red LED on the antenna, which lights up
briefly every second during interference-free reception. For alignment, the antenna must be connected
to the target system as described in chapter 2.2. In addition, the reception service must be started, so
that the TTY-RS232 converter is supplied with energy. The antenna frame permits any alignment of
the antenna as required.